Grimme's DFT-D3 Functionals in ADF and BAND

Stefan Grimme's latest dispersion correction is now available in the development snapshots of ADF and BAND. Grimme and his coworkers at the Universität Münster outlined the parameterization of this new correction, dubbed DFT-D3, in a recent issue of The Journal of Chemical Physics 132, 154104 (2010). Here they list the advantages of the new method as the following:

It is less empirical, i.e., the most important parameters are computed from first principles by standard Kohn-Sham (KS)-(TD)DFT.

The approach is asymptotically correct with all DFs for finite systems (molecules) or nonmetallic infinite systems. It gives the almost exact dispersion energy for a gas of weakly interacting neutral atoms and smoothly interpolates to molecular (bulk) regions.

It provides a consistent description of all chemically relevant elements of the periodic system (nuclear charge Z = 1-94).

Atom pair-specific dispersion coefficients and cutoff radii are explicitly computed.

Coordination number (geometry) dependent dispersion coefficients are used that do not rely on atom connectivity information (differentiable energy expression).

It provides similar or better accuracy for "light" molecules and a strongly improved description of metallic and "heavier" systems.

Above: The adsorption energy of perylene-tetracarboxylic-dianhydride (PTCDA) on a gold (111) surface as a function of distance. Results without (PBE) and with dispersion corrections (PBE-D2, PBE-D3) are shown. The experimental distance is 3.27Å. The vdW-DF result is from PCCP, 12, 4759 (2010).

The article continues by, among other things, demonstrating how this new DFT-D version decreases the mean absolute deviations for a benchmark set of non-covalent interactions by 15-40% over the previous version. Professor Grimme notes that the more significant errors in dispersion energy can be expected for modeling highly charged systems. See section III-F of the original paper for more details.

DFT-D3 is now available in the development snapshots of ADF and BAND, versions r23091 and later. They can be downloaded at http://www.scm.com/SCMForms/DownloadSnapshots.jsp. Instructions on the use of this functional can be found in the ADF developer's change-log at http://www.scm.com/Downloads/ChangeLog-trunk.html.